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【答案】应助回帖
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超级老快: 金币+100, 翻译EPI+1, ★★★★★最佳答案 2016-11-22 09:12:20
稀土离子的电荷迁移态吸收是一个宽带的形状。当电子从配体（氧与卤素）的充满的分子轨道跃迁至稀土离子内部的部分充满的4f壳层时，在激发光谱或吸收谱上产生较宽的电荷迁移带，谱带位置随环境的改变位移较大，与稀土离子的f-d跃迁是相同的。例如Eu-O的电荷迁移带的来源于从O2-的2p电子到Eu3+的5d轨道的电荷传递作用，这些外层轨道受环境影响比较大。较宽的吸收谱带可以提高对激发光能量的吸收，然后将这部分能量传递给稀土激活剂离子，这是提高稀土离子发光效率的重要途径。
The absorption spectrum for charge-transfer state of rare earth ions is rather broad. Electronic transition from fully occupied molecular orbitals of ligands (oxygen and halogen) to partially occupied intra-4f shell of rare earth ions produces relatively broad charge transfer bands as reflected in both absorption and emission spectra, which is environment sensitive , similar to f-d electronic transition of rare earth ions. For example, Eu-O charge transfer bands originated from 2p electrons of O2 to 5d orbital of Eu3+ was heavily influenced by the environment. A relatively broad absorption band increases the efficiency of energy absorption from excitation light, which is then partially transferred to rare earth ions. This an important mechanism that enhances the efficiency of light emission from rare earth ions. |
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